The actor portrayed Finn Hudson, a high school quarterback whose love affair with glee club diva Rachel Berry was a central plot in the show and also spun off a real life romance between Monteith and his co-star Lea Michele.

Celebrity substance abuse confessions – Swimmer Michael Phelps, the most-decorated Olympian of all time, tweeted October 5 that he is taking a break from the sport "to attend a program that will provide the help I need to better understand myself." The announcement came after Phelps was charged on September 30 with driving under the influence of alcohol.

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Celebrity substance abuse confessions – Alisan Porter, the actress best known as the star of 1991's "Curly Sue," opened up about her struggle with alcoholism in a blog post in September. In the personal account, called "The Obligatory Child Star Gets Sober Mom Blog," Porter talks about what led her to seek treatment for alcoholism and that she's been sober since 2007.

Celebrity substance abuse confessions – Actress and model Amber Valletta had her "coming out" as an addict during a recent speech for Mind Body Green. Valletta admitted that she started trying to get high at the age of 8 and said, "My hope is that someone, somewhere in this room, out of this room, will hear something that will help them and perhaps get them out of the shadows and the darkness of addiction and bring them into the light."

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Celebrity substance abuse confessions – Shia LaBeouf's recent bizarre behavior culminated in his being arrested in New York and charged with harassment, disorderly conduct and criminal trespass at the Broadway show "Cabaret." The actor's rep said July 1: "Contrary to previous erroneous reports, Shia LaBeouf has not checked into a rehabilitation facility but he is voluntarily receiving treatment for alcohol addiction. He understands that these recent actions are a symptom of a larger health problem and he has taken the first of many necessary steps towards recovery."

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Celebrity substance abuse confessions – Musician Deryck Whibley has blogged about his problems with alcohol. The Sum 41 group member and former husband of Avril Lavigne said he had been off the scene for a while because he had been hospitalized after "drinking hard every day."

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Celebrity substance abuse confessions – Zac Efron completed a rehab program in 2013 without the media being any wiser about his problems, but the actor's now speaking out about his difficulties with drugs and alcohol. "It's a never-ending struggle," the 26-year-old told The Hollywood Reporter in its May 9 issue.

Celebrity substance abuse confessions – Former "Partridge Family" star David Cassidy was ordered to three months of rehab on March 24 after pleading no contest to a DUI charge from January. It was his second DUI arrest in six months and third since 2011.

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Celebrity substance abuse confessions – The death of Philip Seymour Hoffman and his problems with substance abuse are a reminder that such struggles are not unusual in the movie business.

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Celebrity substance abuse confessions – "Desperate Housewives" actor Shawn Pyfrom wrote about his own struggle with drugs after Hoffman's death. The young actor says in an online letter that he "wasted the time of valuable people, who worked so hard to pull my career to a higher place, by allowing my addictions to tug me out of their grip."

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Celebrity substance abuse confessions – Justin Bieber was booked into a Miami jail after failing a sobriety test January 23. According to Miami Beach Police Chief Raymond Martinez, during his arrest, Bieber "made some statements that he had consumed some alcohol, and that he had been smoking marijuana and consumed some prescription medication" before getting behind the wheel of a yellow Lamborghini.

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Celebrity substance abuse confessions – Country singer Trace Adkins suffered "a setback in his battle with alcoholism" and has entered a rehab facility for help, his representative said January 16.

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Celebrity substance abuse confessions – In a December interview with "Access Hollywood," Demi Lovato went into detail about her dependence on drugs and alcohol. There was a time when Lovato "couldn't go 30 minutes to an hour without cocaine, and I would bring it on airplanes," she said. "I would smuggle it, basically, and just wait until everyone in first class would go to sleep, and I would do it right there." According to Lovato, her rock bottom came at 19, when she filled a soda bottle with vodka to drink at 9 a.m. "I had a moment where I was like, 'Oh, my God ... that is alcoholic behavior," she said.

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Celebrity substance abuse confessions – Lady Gaga revealed on the Elvis Duran radio show in November that she's been quietly dealing with an addiction to marijuana. "I had to stop (smoking pot)," the Mother Monster said. "I was addicted to it. ... Although I think it's the best drug to choose from when you're playing around and experimenting, I just want young kids to know that you actually can become addicted to it, and it's ultimately ... a form of self-medication. I was smoking 15 to 20 marijuana cigarettes a day with no tobacco."

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Celebrity substance abuse confessions – Jada Pinkett-Smith reflected on her Facebook page in September 2013 that addictions plagued her in her younger years. "I had many addictions, of several kinds, to deal with my life issues," she said.

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Celebrity substance abuse confessions – Country star Tim McGraw said in an interview in 2013 that he replaced drinking whiskey with working out to clean his life up.

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Celebrity substance abuse confessions – "Glee" star Cory Monteith was found dead at a hotel in Vancouver on July 13, 2013. Officials gave the cause as "mixed drug toxicity, involving intravenous heroin use combined with the ingestion of alcohol." Monteith had been public about his struggle with addiction and checked into a rehab facility in late March. He told Parade magazine that he started using drugs at 13 and had entered rehab by 19.

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Celebrity substance abuse confessions – Matthew Perry has struggled with an addiction to prescription drugs and alcohol and landed on the cover of People magazine to discuss his road to sobriety. While he was on "Friends," he said, "it would seem like I had it all. It was actually a very lonely time for me, because I was suffering from alcoholism."

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Celebrity substance abuse confessions – "Sex and the City" actress Kristin Davis told Health magazine in 2008 that unlike her cocktail-loving character Charlotte York, she is a recovering alcoholic. The 48-year-old admitted that she was drinking so much, she didn't think she'd live past 30.

Celebrity substance abuse confessions – Jamie Lee Curtis has reportedly said she was once so addicted to prescription pain medicine that she stole some from a relative to help feed the addiction.

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Celebrity substance abuse confessions – Jodie Sweetin, who played innocent Stephanie Tanner on "Full House," documented her drug problems in her memoir "unSweetined." A low point, she said, was using cocaine, meth and ecstasy while on tour to discuss her sobriety.

Celebrity substance abuse confessions – In 2012, Black Eyed Peas singer Fergie told Oprah that her drug use proceeded from ecstasy to crystal meth. She became so paranoid she thought the FBI and SWAT teams were following her before she sought treatment.

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Celebrity substance abuse confessions – She was known for her wholesome role as Laura Ingalls on the television series "Little House on the Prairie," but at her worst Melissa Gilbert was covering up feelings of sadness by drinking up to more than two bottles of wine a night, the actress told More magazine.

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Celebrity substance abuse confessions – "Harry Potter" star Daniel Radcliffe told GQ magazine that he had his last drink in 2010. "There were a few years there when I was just so enamored with the idea of living some sort of famous person's lifestyle that really isn't suited to me."

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Celebrity substance abuse confessions – Kristen Johnston talked about her addiction to drugs and alcohol in her 2012 memoir "Guts" and admitted she was depressed during her time on "3rd Rock From the Sun." "And you're not supposed to be," she said. "You can't tell anybody, 'I'm so bummed you gave me an Emmy.' You can't be sad when you're being celebrated. So it was a big conflict and there's no shrink that can understand it."

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Celebrity substance abuse confessions – Samuel L. Jackson was reportedly able to portray crack addict Gator in "Jungle Fever" so authentically because of his own struggles with drugs and alcohol. He landed the breakout role two weeks after leaving rehab.

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Celebrity substance abuse confessions – Actress Kelly Preston, right, has said she gave up drugs and alcohol to be a better mother to her kids and better wife to John Travolta. "I don't drink anymore. I don't smoke anymore. I don't do drugs anymore. All of those come with an 'anymore.' I used to do everything and a lot of everything," she said.

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Celebrity substance abuse confessions – Jane Lynch wrote about her addictions to alcohol and cough syrup in her memoir "Happy Accidents." She told Access Hollywood in 2013 that she has been sober for 21 years.

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Celebrity substance abuse confessions – Sir Elton John told USA Today that he swore off drugs and alcohol in 1990. He said, "If I ever find myself in a situation where there are drugs, I can smell the cocaine. I can feel it in the back of my throat, that horrible feeling of taking the first hit of cocaine. And I leave."

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Celebrity substance abuse confessions – For those who may not remember because she has so completely turned herself around, Drew Barrymore entered rehab at the tender age of 13. Most fans were unaware that the then beloved child star partied so hard. She chronicled her early struggles in her memoir "Little Girl Lost."

Celebrity substance abuse confessions – Backstreet Boys member A.J. McLean last checked into rehab in 2011. He had previously been treated for depression, anxiety and excessive alcohol consumption.

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Celebrity substance abuse confessions – Country star and "American Idol" judge Keith Urban told Oprah in 2010 that his wife Nicole Kidman and several close friends staged an intervention to help him overcome his addiction to cocaine and alcohol.

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Celebrity substance abuse confessions – In 2004, a then 19-year-old Kelly Osbourne reportedly entered rehab for an addiction to painkillers. "The amount of pills that was found in her bag was astounding," her father, Ozzy, said.

Remembering Cory Monteith

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'Glee' star found dead in hotel room

With Monteith's passing, Deadline noted that the show's writers "will consider what to do about the first two episodes in which the return of Monteith's character was to have played an important part."

"The first two episodes of the fifth season had been written before the traditional long summer hiatus, in order to get a jump on the new season; production had been scheduled to start next week," the site reported. "The return of Monteith's character, hunky high school football star turned glee club darling Finn Hudson, was much anticipated by fans, Monteith having been absent from the final episodes of last season to check himself into a drug treatment facility late last March."

"Glee" creator Ryan Murphy has never been one to shy away from either controversy or weaving real life drama into his shows which have included "Nip/Tuck," "American Horror Story" and the now canceled "The New Normal." In April, "Glee" was criticized after airing an episode about a school shooting in the wake of the Sandy Hook elementary school tragedy in Newtown, Connecticut.

That "Glee" will address the tragedy is not in doubt, but how it will remains to be seen.

It won't be the first television show to have to address the loss of a major character. Most recently, TNT's "Dallas" lost Larry Hagman who had played the iconic J.R. Ewing in both the original series and TNT's reboot. That series decided to take his death in November 2012 from complications from cancer as an opportunity for a creative story line that would both address the beloved Hagman's death and thrill fans.

"Larry's death was terribly sad and sudden and we'd certainly rather make the show with him than without him," co-star Jordana Brewster told EW. "That said, I think the writers really came up with a brilliant way to cope with the loss. It could have ruined the show and derailed everyone, but instead they made the best of it and actually came up with some really great stuff."

When actor John Ritter died of an aortic dissection in 2003 while filming his popular series "8 Simple Rules," ABC incorporated his character's death into the show and brought in actors David Spade and James Garner. The show was eventually canceled in 2005.

While Monteith was not the main star of the ensemble cast of "Glee," his character was a central one and a fan favorite. Writing for Vulture, Lauren Hoffman said "The loss of Finn alters the show's landscape permanently and irrevocably."

"Whenever Glee has been at a loss for story in the past, it's circled back to three key relationships: Kurt and Blaine, Brittany and Santana, and Finn and Rachel," Hoffman said. "Monteith's death and Heather Morris' (who played cheerleader Brittany Pierce) departure further destabilize a show already on shaky ground as it struggles to take on a more mature tone following the graduation of several of its main characters from high school."

Having concluded season four, "Glee" has grappled with lower ratings and ingratiating new characters into the hearts of fans. When Monteith's character along with several others graduated, new actors Melissa Benoist, Jacob Artist, Becca Tobin, Blake Jenner and Alex Newell were introduced.

Even before Monteith's death, it was announced that the new group would be bumped up to regulars in season five, while original stars Mark Salling, Amber Riley, Heather Morris and Harry Shum, Jr. would have reduced roles. It was also recently revealed that "American Idol" runner-up Adam Lambert would be joining the show.

There is already fan speculation as to how "Glee" should handle the tragedy. Might the new group of students be pushed more to the forefront in the wake of the loss of Monteith? Selina Wilken, a writer from Hypable which bills itself as being "for fans, by fans," suggested that producers could do anything from allowing Monteith's Finn a happy ending off screen to "breaking the fourth wall" and directly addressing the audience.

"Of course you could argue that there is no 'good' or 'right' way to handle this situation. Right now, in the face of such a devastating tragedy, the future of a TV show seems like the most unimportant thing in the world," she wrote. "But at the same time, we want Cory Monteith to be remembered. We want his life celebrated. We want Glee to honour both Monteith and his character, because that's what he deserved."

No matter how the storyline is altered to accommodate Monteith's death, it is clear that the loss is a huge one for the show.

"The musical comedy faces special circumstances, appealing as it does to a youthful demographic, swaths of which idolized or even 'carried a torch' for Monteith," wrote TVLine's Matt Webb Mitovich. "Viewers also will know the pain his on-/off-screen love, Lea Michele, herself must feel, every time they see Rachel."